All-Aromatic (AB)n-Multiblock Copolymers via Simple One-Step Melt Condensation Chemistry

2016 ◽  
Vol 49 (22) ◽  
pp. 8549-8562 ◽  
Author(s):  
Qingbao Guan ◽  
Ben Norder ◽  
Liangyong Chu ◽  
Nicolaas A. M. Besseling ◽  
Stephen J. Picken ◽  
...  
Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2063
Author(s):  
Stepan A. Ostanin ◽  
Alexei V. Kalinin ◽  
Yurij Yu. Bratsyhin ◽  
Natalia N. Saprykina ◽  
Vjacheslav V. Zuev

Multiblock copolymers containing linear polydimethylsiloxane or polymethyltrifluoropropylsiloxane and ladder-like polyphenylsiloxane were synthesized in a one-step pathway. The functional homopolymer blocks and final multiblock copolymers were characterized using solution and solid-state multinuclear 1H, 13C, 19F, and 29Si NMR spectroscopy. It was shown that the ladder-like block contains silanol units, which influence the adhesion properties of multiblock copolymers and morphology of their casted films. The adhesion to metals and mechanical properties of multiblock copolymers were tested. The SEM study of casted films of multiblock copolymers shows the variety of formed morphologies, including long-strip-like or globular.


2015 ◽  
Vol 6 (2) ◽  
pp. 1530-1536 ◽  
Author(s):  
Yang Li ◽  
Jiali Hong ◽  
Renjian Wei ◽  
Yingying Zhang ◽  
Zaizai Tong ◽  
...  

Carbon dioxide-based multiblock copolymers were synthesized by a one-pot/one-step three-component polymerization of cyclohexene oxide, ε-caprolactone and CO2via cross-chain exchange reaction at two catalysts.


2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Xiaochao Xia ◽  
Ryota Suzuki ◽  
Tianle Gao ◽  
Takuya Isono ◽  
Toshifumi Satoh

AbstractSwitchable polymerization holds considerable potential for the synthesis of highly sequence-controlled multiblock. To date, this method has been limited to three-component systems, which enables the straightforward synthesis of multiblock polymers with less than five blocks. Herein, we report a self-switchable polymerization enabled by simple alkali metal carboxylate catalysts that directly polymerize six-component mixtures into multiblock polymers consisting of up to 11 blocks. Without an external trigger, the catalyst polymerization spontaneously connects five catalytic cycles in an orderly manner, involving four anhydride/epoxide ring-opening copolymerizations and one L-lactide ring-opening polymerization, creating a one-step synthetic pathway. Following this autotandem catalysis, reasonable combinations of different catalytic cycles allow the direct preparation of diverse, sequence-controlled, multiblock copolymers even containing various hyperbranched architectures. This method shows considerable promise in the synthesis of sequentially and architecturally complex polymers, with high monomer sequence control that provides the potential for designing materials.


Author(s):  
R.P. Goehner ◽  
W.T. Hatfield ◽  
Prakash Rao

Computer programs are now available in various laboratories for the indexing and simulation of transmission electron diffraction patterns. Although these programs address themselves to the solution of various aspects of the indexing and simulation process, the ultimate goal is to perform real time diffraction pattern analysis directly off of the imaging screen of the transmission electron microscope. The program to be described in this paper represents one step prior to real time analysis. It involves the combination of two programs, described in an earlier paper(l), into a single program for use on an interactive basis with a minicomputer. In our case, the minicomputer is an INTERDATA 70 equipped with a Tektronix 4010-1 graphical display terminal and hard copy unit.A simplified flow diagram of the combined program, written in Fortran IV, is shown in Figure 1. It consists of two programs INDEX and TEDP which index and simulate electron diffraction patterns respectively. The user has the option of choosing either the indexing or simulating aspects of the combined program.


Author(s):  
Richard J. Spontak ◽  
Steven D. Smith ◽  
Arman Ashraf

Block copolymers are composed of sequences of dissimilar chemical moieties covalently bonded together. If the block lengths of each component are sufficiently long and the blocks are thermodynamically incompatible, these materials are capable of undergoing microphase separation, a weak first-order phase transition which results in the formation of an ordered microstructural network. Most efforts designed to elucidate the phase and configurational behavior in these copolymers have focused on the simple AB and ABA designs. Few studies have thus far targeted the perfectly-alternating multiblock (AB)n architecture. In this work, two series of neat (AB)n copolymers have been synthesized from styrene and isoprene monomers at a composition of 50 wt% polystyrene (PS). In Set I, the total molecular weight is held constant while the number of AB block pairs (n) is increased from one to four (which results in shorter blocks). Set II consists of materials in which the block lengths are held constant and n is varied again from one to four (which results in longer chains). Transmission electron microscopy (TEM) has been employed here to investigate the morphologies and phase behavior of these materials and their blends.


2006 ◽  
Vol 73 ◽  
pp. 85-96 ◽  
Author(s):  
Richard J. Reece ◽  
Laila Beynon ◽  
Stacey Holden ◽  
Amanda D. Hughes ◽  
Karine Rébora ◽  
...  

The recognition of changes in environmental conditions, and the ability to adapt to these changes, is essential for the viability of cells. There are numerous well characterized systems by which the presence or absence of an individual metabolite may be recognized by a cell. However, the recognition of a metabolite is just one step in a process that often results in changes in the expression of whole sets of genes required to respond to that metabolite. In higher eukaryotes, the signalling pathway between metabolite recognition and transcriptional control can be complex. Recent evidence from the relatively simple eukaryote yeast suggests that complex signalling pathways may be circumvented through the direct interaction between individual metabolites and regulators of RNA polymerase II-mediated transcription. Biochemical and structural analyses are beginning to unravel these elegant genetic control elements.


2010 ◽  
Vol 43 (18) ◽  
pp. 16
Author(s):  
MATTHEW R.G. TAYLOR
Keyword(s):  

2007 ◽  
Vol 0 (0) ◽  
pp. 0-0
Author(s):  
C.W. Kim ◽  
Y.H. Kim ◽  
H.G. Cha ◽  
D.K. Lee ◽  
Y.S. Kang

1980 ◽  
Vol 25 (7) ◽  
pp. 536-538
Author(s):  
LUCIA ALBINO GILBERT
Keyword(s):  

Sign in / Sign up

Export Citation Format

Share Document